Thermochemical and Constitutional Properties of Al-Si-Mg-Cu Alloys

这个特殊项目的总体目标-在整个资助期的初始提案中设定-仍然是旨在确定Al-Si-Mg-Cu系统相关合金的热化学和组成特性的系统研究。通过在这些系统中逐步推进的热力学计算，对关键合金样品进行了专门的实验研究。将calphad型计算与选定的实验相结合，将对最终的calphad型热力学模型具有决定性作用，该模型具有对热化学性质和整个相图的一致描述，具有最高的精度。提供这些直接确定的材料数据对于定量理解铝合金技术相关凝固的总体目标至关重要，并减少凝固模型中固有的模糊性，在这些模型中，这些特性经常被误用为拟合参数。在提议期间，工作将集中在Cu-Si二元和Al-Cu-Si三元体系和选定的四元数据上。结合“相图的热力学评价”项目，将新的实验结果与“热力学数据的从头算预测”中的从头算能量计算相结合，取代仅基于文献数据的初步热力学描述。第四Q相及其相平衡将被更详细地研究。在第一轮“临界凝固实验”的密切配合下，首次实现了Q作为单相的复杂制备后，关键热力学数据（熔合热）得到了响应。将确定第四分解反应和相关温度，以及作为温度函数的热容量。为此，我们提供了一系列精密的实验室设备，专门设计用于热力学和合金性质的高精度实验研究。

The global goal of this particular project- set in the initial proposal for the entire funding period - remains the systematic research aiming at the determination of thermochemical and constitutional properties for pertinent alloys of the Al-Si-Mg-Cu system. Dedicated experimental investigations on key alloy samples, selected by progressively advancing thermodynamic calculations in these systems are employed. This combination of Calphad-type calculations with selected experiments will be decisive for the final Calphad-type thermodynamic modelling with a consistent description of both the thermochemical properties and the entire phase diagram with highest precision. Providing these directly determined materials data is essential to the overall goal of understanding technologically relevant solidification of aluminium alloys quantitatively and reduces the inherent ambiguity in solidification models in which these properties are often misused as fitting parameters.In the proposed period the work will focus on the Cu-Si binary and the Al-Cu-Si ternary system and selected quaternary data. Jointly with the project “Thermodynamic evaluation of phase diagrams", a replacement of the preliminary thermodynamic description, based only on data available in the literature, is aimed at, combining the new experimental results and the ab initio energy calculations from “Ab initio prediction of thermodynamic data”. The quaternary Q phase and its phase equilibria will be investigated in more detail. After the complex preparation of Q as a single phase was achieved for the first time in close cooperation with “Critical solidification experiments” in the first round, the key thermodynamic data (heat of fusion resp. quaternary decomposition reaction and associated temperatures, as well as heat capacity as function of temperature) will be determined. To this purpose a spectrum of sophisticated laboratory equipment, specifically designed for high precision experimental investigation of thermodynamic and constitutional alloy properties is available.